In a UMTS (Universal Mobile Telecommunications System) network, for the purposes of improving spectral efficiency and improving the data rates, system features based on W-CDMA (Wideband Code Division Multiple Access) are maximized by adopting HSDPA (High Speed Downlink Packet Access) and HSUPA (High Speed Uplink Packet Access). For this UMTS network, for the purposes of further increasing high-speed data rates, providing low delay and so on, long term evolution (LTE) has been under study.
In a third-generation system, it is possible to achieve a transmission rate of maximum approximately 2 Mbps on the downlink by using a fixed band of approximately 5 MHz. Meanwhile, in the LTE system, it is possible to achieve a transmission rate of about maximum 300 Mbps on the downlink and about 75 Mbps on the uplink by using a variable band which ranges from 1.4 MHz to 20 MHz. Furthermore, in the UMTS network, for the purpose of achieving further broadbandization and higher speed, successor systems to LTE have been under study (for example, LTE Advanced (LTE-A)). For example, in the LTE-A system, there is a plan to extend the maximum system band of 20 MHz specified in the LTE system up to about 100 MHz.
The LTE system is a system where communication is performed with one or more physical channels shared between plural mobile station apparatuses UE both on the uplink and on the downlink. A channel shared by plural mobile station apparatuses UE is generally referred to as “shared channel” (or it may be called data channel) and in the LTE system, there are uplink PUSCH (Physical Uplink Shared CHannel) and downlink PDSCH (Physical Downlink Shared CHannel).
In this LTE system, in the communication system using the shared channels, it is necessary to inform to which a mobile station apparatus UE the above-mentioned shared channel is assigned per transmission time interval (TTI) (subframe for LTE) by signaling. A downlink control channel for this signaling is defined as a PDCCH (Physical Downlink Control CHannel).
Downlink control information transmitted in this PDCCH includes, for example, downlink scheduling information (see Non Patent Literature 1). This downlink scheduling information includes, for example, allocation information of downlink resource blocks, identification information of a mobile station apparatus UE, the number of streams, information of precoding vector, data size, modulation scheme, information of HARQ (Hybrid Automatic Repeat reQuest). In the mobile station apparatus UE, radio resources to which PDSCHs directed to the mobile station apparatus are assigned are recognized by decoding the PDCCH, thereby being able to recode the radio resources.